During a recent inspection, I came across a corroded water shut-off valve like the one in the photo above. The corrosion was pretty significant—enough that I immediately took a picture and sent it to the homeowner to alert them of the issue. Corrosion like this doesn’t just look bad; it can signal serious problems for your home’s plumbing system.

What Causes This Kind of Corrosion?

This kind of corrosion typically builds up over time due to a slow leak, condensation, or electrolysis between dissimilar metals. Over time, water and air exposure causes the copper and brass components to oxidize, leading to that crusty green and white buildup you see in the image. In some cases, it can also stem from poor initial installation or lack of maintenance.

Why Is This a Problem?

The corrosion itself is more than cosmetic—it’s a red flag. If left unchecked, it can eventually eat through the pipe or valve, causing a leak or even a total failure. This can lead to water damage inside the home, especially if the valve fails when you need to shut off the water in an emergency.

This Will Fail a 4-Point Inspection

In Florida, this kind of corrosion is one of the things that will cause a home to fail a 4-point inspection. Insurance companies want to see that major systems—including plumbing—are in good working condition. When a shut-off valve is this corroded, it signals a lack of maintenance and raises concerns about the risk of future water damage.

Most insurers will not issue or renew a policy if issues like this are found. That’s why it’s so important to get ahead of these problems before you list your home, purchase a new policy, or renew an existing one.

What’s the Fix?

The good news is that a licensed plumber can usually replace the shut-off valve quickly and affordably. In most cases, the fix involves cutting out the corroded section and installing a new valve with proper fittings. This not only makes the system safer but also helps your home pass a 4-point inspection.

Don’t Wait for It to Leak

If you see corrosion like this on your home’s plumbing—even if it’s not currently leaking—don’t wait. Have a licensed plumber inspect and repair it before the damage spreads or it interferes with your insurance coverage.